Wireworm (Agriotes spp.)
Although adult click beetles do eat foliage, their impact is pretty minimal. However their inch long, thin, glossy brown larvae bore holes through the roots and tubers of many plants in late summer and autumn. The larvae are small and white when they hatch, after about 4 weeks, from eggs laid in the summer. They can then spend up to five years eating before they burrow a foot or so into the soil to pupate. Another 4 weeks and the adult emerges which will spend the winter in a miniature cave underground.
It is actually a grassland pest and is often at its worst when an area of grass has recently been converted to vegetable growing
- In young plants, damage to the roots means plants can't get enough water so leaves will wilt, and, in severe cases, the plant may die
- Potatoes are riddled with narrow tunnels which fill with soil. These then let in diseases and other pests like millipedes.
Prevention & control
- Removing all traces of previous infected crops will starve them of food
- Getting plants off to a strong start is important. One way to do this is to grow them in modules or pots before planting out when they are more able to cope with an attack
- Cultivate your whole plot, removing all grass
- Regular cultivation , particularly over winter, will expose them to predators
- Cubes of potato or carrot on a stick will attract them so they can be collected up and disposed of regularly.
- Limit damage to potatoes by lifting them as soon as they are aready.
- Nematodes (Heterorhabditis megadis) are available which can conontrol populations but multiple applications may be required